• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

Chemical modification of leukotriene (LT) A4 hydrolase and structral analysis of its active centers.

Research Project

Project/Area Number 07670135
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field General medical chemistry
Research InstitutionUniversity of Tokyo

Principal Investigator

OHISHI Nobuya  University of Tokyo, Faculty of Medicine, Associate, 医学部・附属病院, 助手 (30231195)

Co-Investigator(Kenkyū-buntansha) SHIMIZU Takao  University of Tokyo, Faculty of Medicine, Professor, 医学部, 教授 (80127092)
Project Period (FY) 1995 – 1996
Project Status Completed (Fiscal Year 1996)
Budget Amount *help
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1995: ¥1,400,000 (Direct Cost: ¥1,400,000)
KeywordsLeukotriene A4 hydrolase / Aminopeptidase / Bestatin / N-acetylimidazole / Active center / 化学修飾
Research Abstract

LTA4 hydrolase is a bifunctional enzyme which has both LTA4 hydrolase activity and aminopeptidase activity. These two catalytic activities showed different kinetic properties inclding pH dependencies and selective stimlatory effect of Cl on aminopeptidase activity. In inhibitor experiments, leucinthiol exhibited competitive inhibition on both catalytic activities, while bestatin showed uncompetitive inhibition on LTA4 hydrolase activity and competitive inhibition on aminopeptidase activity, which indicates that the binding sites of LTA4 and peptides on the enzyme is not identical.
As a means of identifying amino acid residues contributing to catalytic activities, we performed acetylation of the enzyme with N-acetylimidazole. Both catalytic activities were inactivated by this modification, which cold be recovered by the tretment with netral hydroxylamine. Frthermore, both activities could be protected from inactivation by bestatin. These results sggested that acetylation of Tyr-or Cys-residues located in or near the bestatin binding site was responsible for the inactivation of both catalytic activities. The UV spectrophotometrical quantification of O-acetyl-Tyr resulting from acetylation of the enzyme indicated that 1.7-Tyr-residues were protected from acetylation by bestatin. Titration of sulfydoryl groups with DTNB showed the presence of 9-SH-residues in both native and acetylated enzyme indicating that N-acetylimidazole did not acetylated Cys-residues in the enzyme. Considering these results, acetylation of 2-Tyr-residues located in or near the bestatin binding site resulted in the loss of both catalytic activities. As substrates binding sites for the two catalytic activities are not identical, functional properties of these Tyr-resides may be different in each catalysis.

Report

(3 results)
  • 1996 Annual Research Report   Final Research Report Summary
  • 1995 Annual Research Report
  • Research Products

    (7 results)

All Other

All Publications (7 results)

  • [Publications] 大石展也: "アラキドン酸カスケードをめぐる話題" Annual Review 呼吸器 1997. 60-80 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 南道子: "ロイコトリエンA_4水解酵素の研究" 蛋白質核酸酵素. 印刷中. (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Ohishi, N.: "Recent advances in arachidonic acid cascade research.(in Japanese)" Annual Review Respiratory Diseases. 1997. 60-80 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Minami, M., Ohishi, N., and Shimizu, T.: "Leukotriene A4 hydrolase. (in Japanese)" Protein Nucleic acid Enzyme. (in press.). (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 大石展也: "アラキドン酸カスケードをめぐる話題" Annual Review呼吸器1997. 60-80 (1997)

    • Related Report
      1996 Annual Research Report
  • [Publications] 南 道子: "ロイコトリエンA_4水解酵素の研究" 蛋白質核酸酵素. (印刷中). (1997)

    • Related Report
      1996 Annual Research Report
  • [Publications] Minami,M.: "Amino-acid sequence and tissue distribution of guinea-pig leukotriene A_4 hydrolase." Gene. 161. 249-251 (1995)

    • Related Report
      1995 Annual Research Report

URL: 

Published: 1995-04-01   Modified: 2016-04-21  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi